Shock and vibration-resistant arrangement for cathodes of small heating power



Sept. 2, 1969 K. FUCHS 3,465,195

' SEOCK AND VIBRATION-RESISTANT ARRANGEMENT FOR CATHODES OF SMALJiJOHEATING POWER arch Filed M 1967 FIG. 1

INVENTOR KLAUS FUCHS United States Patent O US. Cl. 313-270 3 Claims ABSTRACT OF THE DISCLOSURE A cathode tube of rectangular cross-section has a pair of spaced parallel side surfaces and a pair of spaced parallel upper and under surfaces perpendicular to the side surfaces. The upper surface has an electron emitting surface. A principal cathode axis extends parallel to and equally spaced from and between the upper and under surfaces and the two side surfaces. The cathode tube has a length extending along the principal cathode axis. A cathode support tube of substantially rectangular cross-section has an upper surface affixed to the central area of the under surface of the cathode tube and extends for a length equal to the length of the cathode tube. A metal heat reflector is positioned around the cathode tube. A reflector support tube coaxially positioned around and afiixed to the cathode support tube supports the reflector in spaced parallel relation with the under surface of the cathode tube. The reflector is equidistantly spaced from the under and side surfaces of the cathode tube.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates to a cathode arrangement for an electron beam producing system. More particularly, the invention relates to a cathode arrangement for an electron beam producing system utilizing low heating power.

It is desirable that the principal cathode axis extend at right angles to the discharge direction of the electron beam, since extended heating elements permit the cathode temperature and the characteristic values of the heating current to be maintained within small tolerances.

Description of the prior art An indirectly heated cathode of the type of the present invention, utilizing low heating power, may be utilized in cathode ray tubes such as, for example, as used in portable transistorized equipment. Precautions must be taken to keep the losses of filament or heating power due to heat transfer and heat radiation as low as possible. If the cathode tube is mounted between two insulating components comprising mica, the heat losses are so great that a cathode with low heating power is not attainable. The cathode tube may be mounted in a cylinder surrounding it by supporting strips. The reflection of the cylinder is supposed to reduce the heat losses, but the large surface of the cylinder increases the heat radiation, so that the heating power cannot be reduced further.

A cathode of cylindrical configuration or of rectangular cross-section may be supported at its ends by a pair of spaced parallel extending supporting strips which are perpendicular to the principal axis of the cathode. The supporting strips have the same length as the cathode and are affixed to an insulating disc which is parallel to the principal axis of the cathode. Flaps or tongues provided in the cathode cylinder are positioned at the base ends thereof. Cathode of this type are a considerable current load in portable equipment. The cathode arrangement is unstable when it is subjected to vibrations or shocks. When 3,465,195 Patented Sept. 2, 1969 assembling or mounting such a cathode arrangement, it is very diflicult to precisely and exactly adjust the distance between the electron emitting surface of the cathode and a reference plane.

SUMMARY OF THE INVENTION The principal object of the present invention is to provide a new and improved cathode arrangement for an electron beam producing system. The cathode arrangement of the present invention avoids the disadvantages of the cathode arrangements of the prior art. The cathode arrangement of the present invention utilizes very low heating or filament power and has great stability. The cathode arrangement of the present invention is readily and facilely adjusted relative to a reference plane. The heat losses of the cathode arrangement of the present invention are considerably reduced.

In accordance with the present-invention, a cathode arrangement for an electron beam producing system having a principal cathode axis at right angles to the discharge direction of the electron beam comprises a cathode tube of substantially rectangular cross-section. The cathode tube has a pair of spaced parallel side surfaces and a pair of spaced parallel upper and under surfaces perpendicular to the side surfaces. The upper surface has an electron emitting surface. A principal cathode axis extends parallel to and equally spaced from and between the upper and under surfaces and the two side surfaces.

.A cathode tube support extending substantially perpendicuarly to the principal cathode axis comprises a cathode support tube of substantially rectangular crosssection having an upper surface aflixed to the under surface of the cathode tube.

The cathode tube has a length extending along the principal cathode axis and the cathode support tube extends for a length substantially equal to the length of the cathode tube. The under surface of the cathode tube has a substantially central area and the upper surface of the cathode support tube is affixed to the under surface of the cathode tube in the central area thereof.

A flange on the upper surface of the cathode support tube has an upper surface aflixed to the under surface of the cathode tube in the central area thereof. A metal heat reflector is positioned around the cathode tube. A reflector support supports the reflector in spaced parallel relation with the under surface of the cathode tube for reflecting heat toward the cathode tube. The reflector is equidistantly spaced from the under and side surfaces of the cathode tube. The reflector support comprises a reflector support tube coaxially positioned around the cathode support tube having an upper surface affixed to the under surface of the reflector. The cathode support tube and the reflector support tube are ailixed to each other to prevent axial or rotational movement of the cathode support tube.

BRIEF DESCRIPTION OF THE DRAWING In order that the present invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, wherein:

'FIG. 1 is a side view, partly in section, of an embodiment of the cathode arrangement of the present invention;

FIG. 2 is a top plan view of the embodiment of FIG. 1',

FIG. 3 is a side view on a larger scale and partly in section, of parts of the cathode arrangement of FIGS. 1 and 2 and parts not shown in FIGS. 1 and 2; and

FIG. 4 is a side view of the embodiment of FIG. 3 revolved degrees about its axis.

3 DESCRIPTION OF THE PREFERRED EMBODIMENT In the figures, a cathode tube 1 has a rectangular cross-section having a pair of spaced parallel side surfaces 1a and 1b and a pair of spaced parallel upper and under surfaces 10 and 1d, respectively, perpendicular to said side surfaces (FIG. 3). The upper surface 1c of the cathode tube 1 has an electron emitting surface 2. The principal cathode axis 3 (FIG. 2 and 3) extends parallel to and equally spaced from and between the upper and under surfaces 1c and 1d and the two side surfaces 1a and 1b. The length of the cathode tube 1 extends and is measured along the principal cathode axis 3.

A cathode support tube 4 (FIGS. 1 and 3) extends perpendicularly to the principal cathode axis 3 for a length substantially equal to the length of the cathode tube 1. The cathode support tube 4 is of rectangular cross-section and has an upper surface affixed to the under surface 1d of the cathode tube 1 in the central area of said under surface.

A flange 5 (FIG. 1) on the upper surface of the cathode support tube 4 has an upper surface aflixed to the under surface 1d of the cathode tube 1 in its central area. The cathode support tube 4 is mounted in a ceramic insulator 6 (FIGS. 1 and 2) by any suitable means such as, for example, a flanged cylindrical fastener or rivet 7 (FIGS. 1 and 2). An electrically conductive lead 8 may be electrically connected to the cathode tube 1 via an electrically conductive member 9 (FIG. 1) and the cathode support tube 4.

The ceramic insulator 6 has a central recess formed therethrough, in which the cathode support tube 4 is coaxially mounted by the rivet 7, and a plurality of protruding portions 10a, 10b, 10c and 10d (FIGS. 1 and 2) formed therein around most of the central recess. The upper annular sectional surface 11 (FIG. 1) of the protruding portions 10a, 10b, 100 of the ceramic insulator 6 may be utilized as a reference plane for the adjustment of the cathode tube 1 in position.

A heating element or filament (not shown in the figures) is mounted in the cathode tube 1. Electrically conductive leads 12 and 13, for energizing the filament of the cathode, are connected to said filament via the open ends of the cathode tube 1 and to electrically conductive prongs 14 and 15, respectively, via electrical connectors 16 and 17, respectively (FIGS. 1 and 2). The prongs 14 and are mounted in the ceramic insulator 6.

As shown in FIGS. 3 and 4, a metal heat reflector 18 is positioned around the cathode tube 1. The reflector 18 is supported in spaced parallel relation with the under surface 1d of the cathode tube 1 by a reflector support tube 19. The reflector 18 reflects heat toward the cathode tube 1 and is equidistantly spaced from the under and side surfaces 1d and 1a and 1b of said cathode tube. The reflector 18 thus functions to retain heat which would otherwise be dissipated by radiation.

The reflector support tube 19 is coaxially positioned around the cathode support tube 4 and has an upper surface aflixed to the under surface of the reflector 18. The cathode support tube 4 and the reflector support tube 19 are aflixed to each other by any suitable means such as, for example, a plug or indented portion 21 and/ or a crimped or indented band area 22 of said reflector support tube.

The cathode arrangement of the present invention is suitably dimensioned for utilization in existing cathode ray tubes. It is thus technologically possible to exchange existing cathode arrangements for the cathode arrangement of the present invention in existing equipment. The cathode arrangement of the present invention may be installed after the other electrodes have been assembled. The installation and assembly of the cathode arrangement is readily and facilely accomplished with great precision and exactness. The cathode arrangement is readily centered and is adjusted relative to the reference plane provided by the upper surface 11 of the protruding portions 10a, 10b, 10c and 10d of the ceramic insulator 6. When the cathode arrangement is suitably adjusted and inserted relative to the reference plane, it may be mounted in a Wehnelt cylinder, which functions as the control electrode, and is suitably secured in position with the desired exact spacing between the emitting surface 2 of the cathode tube 1 and the control diaphragm.

The substantially increased moment of resistance, the considerably decreased cross-sectional area and the smaller surface of the cathode arrangement of the present invention, compared to known cathode arrangement supports or mountings which utilize a pair of flat supporting strips at the ends of the cathode tube, considerably improve the stability of the cathode arrangement of the present invention and considerably reduce its heat loss or dissipation.

While the invention has been described by means of a specific example and in a specific embodiment, I do not wish to be limited thereto, for obvious modification will occur to those skilled in the art without departing from the spirit and scope of the invention.

What is claimed is:

1. A cathode arrangement for an electron beam producing system having a principal cathode axis at right angles to the discharge direction of the electron beam, said cathode arrangement comprising a cathode tube of substantially rectangular cross-section having a pair of spaced parallel side surfaces, a pair of spaced parallel upper and under surfaces perpendicular to said side surfaces, said upper surface having an electron emitting surface; mounting support member spaced from said under surface; and cathode tube supporting means extending substantially perpendicularly to the principal cathode axis, said cathode tube supporting means comprising a cathode support tube having its upper end affixed to a central area of the under surface of said cathode tube and its lower portion aflixed in said mounting support member.

2. A cathode arrangement as claimed in claim 1, further comprising a flange on the upper end of said cathode support tube, said flange being affixed to said under surface of said cathode tube in the central area thereof.

3. A cathode arrangement according to claim 1 further comprising heat reflector disposed in spaced relation around said side and under surfaces of said cathode tube, reflector support tube coaxially positioned around said cathode support tube and having its upper end affixed to a central area of the under surface of said reflector, said reflector support tube being aflixed in said mounting support member and positively secured to said cathode support tube by compressing at least two opposite surface portions thereof against said cathode support tube.

References Cited UNITED STATES PATENTS 2,378,569 6/1945 Messner et al. 313337 X 3,092,748 6/ 1963 Dickson et a1. 313337 X 3,175,118 3/1965 Ney 313-337 X 3,197,667 7/1965 Almer et a1. 313-270 X 3,389,290 6/1968 Susumu Yoshida 313337 X JOHN W. HUCKERT, Primary Examiner ANDREW J. JAMES, Assistant Examiner U.S. Cl. X.R. 

